The invention relates to an electric reflector lamp provided with:
a rotationally symmetrical lamp vessel comprising:
an axis of symmetry and a greatest diameter transverse to this axis, PA1 a neck-shaped first portion behind the greatest diameter, which portion carries a lamp cap provided with contacts, PA1 a mirror-coated second portion which extends between the first portion and the greatest diameter and merges fluently into the first portion, which second portion extends in a direction transverse to rather than longitudinally along the axis and is, in axial cross-section, substantially curved according to a circular arc whose centre of curvature lies in front of the greatest diameter in a region extending away from the axis of symmetry, PA1 a mirror-coated third portion which merges fluently into the second portion and which extends in front of the greatest diameter in a direction longitudinally along rather than transverse to the axis of symmetry, which third portion, in axial cross-section, is substantially curved according to a circular arc whose centre of curvature lies behind the greatest diameter at the other side of the axis of symmetry, PA1 opposite the first portion, a translucent fourth portion adjoining the third portion, PA1 a light source arranged around the axis of symmetry near the greatest diameter, PA1 current supply conductors extending from the light source to contacts at the lamp cap.
Such a lamp is known from U.S. Pat. No. 4,788,469.
The lamp vessel of the known lamp has a shape which renders it suitable for being provided with various coatings in order to obtain a lamp which is suitable for one of various applications each time. An important application is that of a reflector lamp, which is obtained by providing the second and the third portion of the lamp vessel with a mirror coating. The object of this lamp is to provide a light beam with a high luminous flux and a high luminous intensity in the beam centre.
The lamp vessel of the known lamp was specifically designed for a helical incandescent body as the light source, which body is arranged transversely near the greatest diameter, bent around the axis of symmetry. The centre of curvature of the circular arc according to which the second portion of the lamp vessel is curved and said circular arc itself are on opposing sides of the axis of symmetry is this case.